CN111391814A - Control device for hybrid vehicle - Google Patents

Abstract

The present invention provides a control device for a hybrid vehicle, comprising: a travel control unit (463, 462, 465) that controls the engine (1) and the motor (2) in accordance with the required driving force and controls the brake device (6); and a determination unit (461) that determines whether or not it is possible to generate the required driving force while maintaining the motor travel, during motor travel using only the drive of the motor (2), during engine travel using only the drive of the engine (1), and during hybrid travel using both the drive of the motor (2) and the drive of the engine (1), during parking drive in which the hybrid vehicle (100) is parked in the predetermined space (111). When a determination unit (461) determines that the required driving force cannot be generated while the motor is kept running, a running control unit (463, 462, 465) reduces the driving force of the motor (2), activates the brake device (6) and starts the engine (1), and releases the operation of the brake device (6) after the engine (1) is started.

Description

Control device for hybrid vehicle

Technical Field

The present invention relates to a control device for a hybrid vehicle that controls a traveling operation of the hybrid vehicle.

Background

The hybrid vehicle has a motor and an engine as travel drive sources. As a control device for this hybrid vehicle, a device has been known in which an engine is started as needed during traveling by a motor. Such a device is described in patent document 1, for example. In the device described in patent document 1, when the accelerator opening degree is increased in a state where the vehicle is stopped due to a difference in level of the road surface during traveling by the motor, the engine is started to overcome the difference in level, and the engine is independently operated at a rotation speed corresponding to the accelerator opening degree.

However, in the device described in patent document 1, since the engine is started to increase the driving force during the running by the motor, there is a possibility that the actual driving force exceeds the target driving force and overshoot occurs. Therefore, the device described in patent document 1 is difficult to apply to driving that requires positional accuracy of a vehicle (for example, positional accuracy of about several tens mm to several hundreds mm) different from general driving, such as parking driving in which a vehicle is parked in a predetermined space.

Documents of the prior art

Patent document 1: japanese patent laid-open No. 2012 and 046106 (JP 2012-046106A).

Disclosure of Invention

One aspect of the present invention is a control device for a hybrid vehicle including an engine and a motor as travel drive sources, and a brake device that applies a braking force to stop the vehicle, the control device including: a travel control unit that controls the engine and the motor in accordance with the required driving force and controls the brake device; and a determination unit that determines whether or not the required driving force can be generated while maintaining the motor running state, in a parking operation in which the hybrid vehicle is parked in a predetermined space, when the motor runs in a motor running mode in which the hybrid vehicle is driven only by the motor, an engine running mode in which the hybrid vehicle is driven only by the engine, and a hybrid running mode in which the hybrid vehicle is driven by both the motor and the engine. When the determination unit determines that the required driving force cannot be generated while the motor is kept running, the running control unit decreases the driving force of the motor, activates the brake device and the engine, and releases the operation of the brake device after the engine is activated.

Drawings

The objects, features and advantages of the present invention are further clarified by the following description of the embodiments in relation to the accompanying drawings.

Fig. 1 is a diagram showing a schematic configuration of a travel drive system of a hybrid vehicle according to an embodiment of the present invention.

Fig. 2 is a block diagram schematically showing the overall configuration of a vehicle control system including a control device according to an embodiment of the present invention.

Fig. 3 is a plan view showing an example of a traveling operation of a vehicle to which a control device for a hybrid vehicle according to an embodiment of the present invention is applied.

Fig. 4 is a side view showing a part of the operation of fig. 3.

Fig. 5 is a diagram showing an example of an operation of a reference example of a control device for a hybrid vehicle according to an embodiment of the present invention.

Fig. 6 is a block diagram showing a configuration of a main part of a control device of a hybrid vehicle according to an embodiment of the present invention.

Fig. 7 is a flowchart showing an example of processing executed by the controller of fig. 6.

Fig. 8 is a timing chart showing an example of the operation of the control device of the hybrid vehicle according to the embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described below with reference to fig. 1 to 8. A control device according to an embodiment of the present invention is applied to a hybrid vehicle having an engine and a motor as a travel drive source. The hybrid vehicle may be a front-wheel drive vehicle in which the right and left front wheels are drive wheels, a rear-wheel drive vehicle in which the right and left rear wheels are drive wheels, or a four-wheel drive vehicle in which all four wheels are drive wheels. In the case of a four-wheel drive vehicle, for example, the front wheels may be driven by either an engine or a motor, and the rear wheels may be driven by a motor.

Fig. 1 is a diagram showing a schematic configuration of a travel drive system of a hybrid vehicle according to an embodiment of the present invention. As shown in fig. 1, a hybrid vehicle (also simply referred to as a vehicle) HV includes: the vehicle drive system includes an engine 1, a motor 2, a transmission 3, a clutch 4, a battery 5, and a brake device 6.

The engine 1 is an internal combustion engine (e.g., a gasoline engine) that generates rotational power by mixing intake air supplied through a throttle valve and fuel injected from an injector at an appropriate ratio, igniting the mixture with an ignition plug or the like, and burning the mixture. In addition, various engines such as a diesel engine can be used instead of the gasoline engine. The intake air amount is adjusted by a throttle valve, and the opening degree of the throttle valve is changed by driving an engine actuator (throttle actuator). The driving of the engine 1, that is, the opening degree of the throttle valve and the injection amount (injection timing, injection time) of the fuel injected from the injector are controlled by a controller (fig. 2).

A clutch 4 that operates by hydraulic pressure, electromagnetic force, or the like is provided between the engine 1 and the transmission 3. Power is transmitted or not transmitted between the engine 1 and the transmission 3 by the operation, i.e., connection or disconnection, of the clutch 4. The operation of the clutch 4 is controlled by a controller (fig. 2).

The electric motor 2 is electrically connected to the battery 5 via a power control unit (not shown) including an inverter, and functions as a motor driven by electric power supplied from the battery 5, and as a generator driven to generate electric power during braking and storing the generated electric power in the battery 5. That is, the motor 2 functions as a motor generator. In addition, the battery 5 may be replaced with another power storage device such as a capacitor. The power control unit is controlled by a controller (fig. 2), thereby controlling the driving of the motor 2 and the charging and discharging of the battery 5.

The transmission 3 includes a hydraulic device driven by hydraulic pressure, changes the rotational speed of an input shaft rotationally driven by the engine 1 or the electric motor 2 in accordance with the driving of the hydraulic device, transmits the changed rotational speed to an output shaft 3a, and converts the torque input by the engine 1 or the electric motor 2 to transmit the converted torque to the output shaft 3 a. The transmission 3 can be a step-variable transmission that is manually or automatically changed to any one of a plurality of gears having different gear ratios, or a continuously variable transmission that can change the gear ratio steplessly. The torque transmitted to the output shaft 3a is transmitted to the left and right drive wheels 7 via, for example, a differential mechanism, whereby the vehicle 100 travels. The drive of the transmission 3 (hydraulic device) is controlled by a controller (fig. 2).

The brake device 6 is constituted by, for example, a disc brake that operates by hydraulic pressure, and the rotation of the drive wheels 7 can be forcibly stopped by the operation of the brake device 6. The operation of the braking device 6 is controlled by a controller (fig. 2).

The vehicle 100 configured as above is capable of running in a plurality of driving modes. Specifically, the vehicle can travel in an engine mode (engine travel) in which only the engine 1 is used as a travel drive source, an EV mode (motor travel) in which only the motor 2 is used as a travel drive source, and a hybrid mode (hybrid travel) in which both the engine 1 and the motor 2 are used as drive sources. The driving mode is automatically switched according to the driving force required by vehicle 100 (required driving force), the amount of charge of battery 5, and the like. For example, the EV mode is switched during low-speed running and low-load running, and the engine mode or the hybrid mode is switched during high-load running. Even during low-load running, when the battery 5 needs to be charged, the engine mode or the hybrid mode is switched.

In the present embodiment, the vehicle 100 is configured as a vehicle having an autonomous driving function (autonomous vehicle). The vehicle 100 can travel not only in an automatic driving mode in which the driver is not required to perform driving operation, but also in a manual driving mode in which the driver performs driving operation.

Fig. 2 is a block diagram schematically showing a basic overall configuration of a vehicle control system 101 that controls an autonomous vehicle 100. As shown in fig. 2, the vehicle control system 101 mainly includes a controller 40, and an external sensor group 31, an internal sensor group 32, an input/output device 33, a GPS device 34, a map database 35, a navigation device 36, a communication unit 37, and a travel actuator AC, which are communicably connected to the controller 40, respectively.

The external sensor group 31 is a general term for a plurality of sensors (external sensors) that detect an external condition that is a peripheral condition of the vehicle 100. For example, the external sensor group 31 includes: a laser radar that measures scattered light with respect to irradiation light in all directions of the vehicle 100 to measure a distance from the vehicle 100 to a peripheral obstacle, a radar that detects another vehicle, an obstacle, and the like in the periphery of the vehicle 100 by irradiating electromagnetic waves and detecting reflected waves, and a camera that is mounted on the vehicle 100, includes an imaging element such as a CCD and a CMOS, and images the periphery (front, rear, and side) of the vehicle 100.

The internal sensor group 32 is a general term for a plurality of sensors (internal sensors) that detect the traveling state of the vehicle 100. For example, the internal sensor group 32 includes: a vehicle speed sensor that detects a vehicle speed of vehicle 100, an acceleration sensor that detects acceleration in the front-rear direction and acceleration in the left-right direction of vehicle 100, respectively, an engine speed sensor that detects a speed of engine 1, a yaw rate sensor that detects a rotational angular velocity at which the center of gravity of vehicle 100 rotates about the vertical axis, a throttle opening sensor that detects an opening degree of a throttle valve (throttle opening degree), and the like. The internal sensor group 32 also includes sensors that detect driving operations of the driver in the manual driving mode, such as an operation of an accelerator pedal, an operation of a brake pedal, a steering operation, and the like.

The input/output device 33 is a generic term for a device that inputs a command from the driver and outputs information to the driver. For example, the input/output device 33 includes: various switches for allowing the driver to input various commands by operating the operation member, a microphone for allowing the driver to input commands by voice, a display unit for providing information to the driver via a display image, a speaker for providing information to the driver by voice, and the like. The various switches include a manual/automatic changeover switch that instructs to perform any one of an automatic driving mode and a manual driving mode.

The manual/automatic changeover switch is configured as a switch that can be manually operated by a driver, for example, and outputs a command for changing over to an automatic driving mode in which the automatic driving function is activated or a manual driving mode in which the automatic driving function is deactivated in accordance with a switch operation. When the predetermined running condition is satisfied, the instruction to switch from the manual drive mode to the automatic drive mode or to switch from the automatic drive mode to the manual drive mode may be given regardless of the operation of the manual/automatic changeover switch. That is, mode switching may be automatically performed by automatically switching through a manual/automatic changeover switch instead of manually.

The GPS device 34 includes a GPS receiver that receives positioning signals from a plurality of GPS satellites, and measures the absolute position (latitude, longitude, and the like) of the vehicle 100 from the signals received by the GPS receiver.

The map database 35 is a device for storing general map information used in the navigation device 36, and is constituted by a hard disk, for example. The map information includes: position information of a road, information of a road shape (curvature, etc.), and position information of an intersection or a fork. The map information stored in the map database 35 is different from the high-precision map information stored in the storage unit 42 of the controller 40.

The navigation device 36 is a device that searches for a target route on a road to a destination input by a driver and performs guidance along the target route. The input of the destination and the guidance along the target route are performed by the input/output device 33. The target route is calculated based on the current position of the own vehicle obtained by the GPS device 34 and the map information stored in the map database 35.

The communication unit 37 communicates with various servers not shown in the drawings via a network including a wireless communication network such as an internet line, and acquires map information, traffic information, and the like from the servers at regular intervals or at arbitrary timing. The acquired map information is output to the map database 35 and the storage unit 42, and the map information is updated. The acquired traffic information includes traffic jam information, signal information such as the remaining time of the signal changing from red to green, and the like.

The actuator AC is a travel actuator for controlling travel of the vehicle 100. The actuator AC includes various actuators that operate according to electric signals from the controller 40. For example, an engine actuator for adjusting the opening degree of a throttle valve of the engine 1, the electric motor 2, a transmission actuator for driving the transmission 3, a clutch actuator for driving the clutch 4, a brake actuator for driving the brake device 6, a steering actuator for driving the steering device, and the like.

The controller 40 is constituted by an Electronic Control Unit (ECU). Note that a plurality of ECUs having different functions, such as an engine control ECU and a transmission control ECU, may be provided separately, but fig. 2 shows the controller 40 as a set of these ECUs for convenience. The controller 40 includes a computer having an arithmetic unit 41 such as a CPU, a storage unit 42 such as a ROM, a RAM, and a hard disk, and other peripheral circuits not shown.

The storage unit 42 stores high-precision detailed map information including center position information of a lane, boundary information of a lane position, and the like. More specifically, road information, traffic control information, residence information, facility information, telephone number information, parking lot information, and the like are stored as the map information. The road information includes: information indicating road types such as an expressway, a toll road, and a national road, information such as the number of lanes of a road, the width of each lane, the gradient of a road, the three-dimensional coordinate position of a road, the curvature of a curve of a lane, the positions of a junction and a branch of a lane, and a road sign. The traffic control information includes: and information on whether the lane is restricted from traveling or prohibited from passing through due to construction or the like. The storage unit 42 also stores information such as a shift map (shift line map) serving as a reference of the shifting operation, programs of various controls, and thresholds used in the programs.

The calculation unit 41 has a vehicle position recognition unit 43, an external recognition unit 44, an action plan generation unit 45, and a travel control unit 46 as functional configurations.

The vehicle position recognition unit 43 recognizes the position of the vehicle 100 (vehicle position) on the map based on the position information of the vehicle 100 acquired by the GPS device 34 and the map information of the map database 35. The own vehicle position may be identified with high accuracy by using the map information (information such as the shape of the building) stored in the storage unit 42 and the peripheral information of the vehicle 100 detected by the external sensor group 31 to identify the own vehicle position. When the vehicle position can be measured by a sensor provided outside on the road or near the road, the vehicle position can be identified with high accuracy by communicating with the sensor via the communication unit 37.

The external recognition unit 44 recognizes an external situation around the vehicle 100 from a signal from the external sensor group 31 such as a laser radar, a camera, or the like. For example, the position, speed, acceleration, position of a nearby vehicle (front vehicle, rear vehicle) that is traveling around the vehicle 100, position of a nearby vehicle that is parked or stopped around the vehicle 100, and position, state, and the like of other objects are recognized. Other objects include: signs, annunciators, boundary lines of roads, stop lines, buildings, railings, utility poles, billboards, pedestrians, bicycles, and the like. The states of other objects include: the color of the annunciator (red, green, yellow), the speed of movement, orientation of the pedestrian, bicycle, etc.

The action plan generating unit 45 generates a travel track (target track) of the vehicle 100 from the current time to the elapse of a predetermined time, for example, based on the target route calculated by the navigation device 36, the own vehicle position recognized by the own vehicle position recognition unit 43, and the external situation recognized by the external environment recognition unit 44. When a plurality of trajectories exist as candidates of the target trajectory on the target route, the action plan generating unit 45 selects an optimum trajectory that satisfies the law and meets the criteria for efficient and safe travel, and sets the selected trajectory as the target trajectory. Then, the action plan generating unit 45 generates an action plan corresponding to the generated target trajectory.

The action plan includes: travel plan data set per unit time (for example, 0.1 second) during a period from the current time to the elapse of a predetermined time (for example, 5 seconds), that is, travel plan data set in association with the time per unit time. The travel plan data includes position data of the vehicle 100 per unit time and data of the vehicle state. The position data is, for example, data of a target point indicating a two-dimensional coordinate position on a road, and the vehicle state data is vehicle speed data indicating a vehicle speed, direction data indicating an orientation of the vehicle 100, and the like. The travel plan is updated per unit time.

The action plan generating unit 45 generates the target trajectory by connecting the position data per unit time in chronological order until a predetermined time (for example, 5 seconds) has elapsed from the current time. At this time, the acceleration per unit time (target acceleration) is calculated from the vehicle speed of each target point per unit time on the target trajectory (target vehicle speed). In other words, the action plan generating unit 25 calculates the target vehicle speed and the target acceleration. The target acceleration may be calculated by the travel control unit 46.

The travel control unit 46 controls the actuator AC so that the vehicle 100 travels along the target trajectory generated by the action plan generation unit 45 at the target vehicle speed and the target acceleration in the autonomous driving mode. That is, the engine actuator, the motor 2, and the like are controlled so that the vehicle 100 passes through the target point per unit time. The running control unit 46 switches the driving mode to the EV mode during low-load running, and switches the driving mode to the engine mode or the hybrid mode during high-load running. The driving mode is switched from the EV mode to the engine mode or the hybrid mode also in accordance with the charge amount of the battery 5.

Fig. 3 is a plan view showing an example of a running operation of vehicle 100 to which the control device for a hybrid vehicle according to the present embodiment is applied. Fig. 3 shows an example in which the vehicle 100 traveling on the road 110 is parked laterally (in a direction perpendicular to the lane) in the parking lot 111 facing the road 110 by automatic driving. Specifically, for example, parking is performed in such a manner that a parking lot 111 at a predetermined position is set as a destination of the autonomous vehicle 100, and the vehicle 100 moves to the parking lot 111 by autonomous driving. More specifically, the vehicle 100 once passes in front of the parking lot 111 as indicated by an arrow a1, recognizes the position of the parking lot 111 with a vehicle-mounted camera or the like, and then enters the parking lot 111 by traveling backward as indicated by an arrow a 2. In addition, the vehicle 100 may also enter the parking lot 111 not by backward travel but by forward travel.

The parking lot 111 is, for example, a so-called coin-operated parking lot that charges a fee in units of time. Fig. 4 is a side view showing a state where the vehicle 100 is parked in the parking lot 111. In fig. 4, the front wheels and the rear wheels are denoted by 7F and 7R, respectively. As shown in fig. 4, a parking lot 111 (parking space) is provided with a step portion 112, that is, a lock plate (fender), over which only the rear wheels 7R of the vehicle 100 entering the parking lot 111 in the direction of arrow a3 pass. When a predetermined time has elapsed after the rear wheel 7R has passed, the lock plate is raised from the release position (solid line) to the lock position (broken line), and the vehicle 100 in this state is prohibited from being taken out of the garage.

On the rear side of the step portion 112 (locking plate) in the forward direction (the direction of arrow a 3) when the vehicle is parked, a stopper 113 that abuts against the rear wheel 7R to restrict the rearward movement of the vehicle 100 is provided. The height of the stopper 113 is higher than the height of the release position of the lock plate. By providing the stopper 113, the vehicle 100 can be prevented from traveling backward, and the vehicle 100 can be prevented from colliding with, for example, a rear obstacle 114.

During parking travel, the vehicle control system 101 accurately moves the vehicle 100 to a parking space from the automatic driving position while checking surrounding conditions with a camera or the like. Therefore, the parking travel is performed at a low speed while repeating the start and stop. In the present embodiment, the parking travel is mainly performed in the EV mode.

However, in the EV mode, it may be difficult to get over the step portion 112 due to insufficient traveling driving force. In particular, when the height of the step portion 112 is higher than the normal height, the parking space is inclined due to the ascending slope, the number of passengers and the number of cargos of the vehicle 100 are larger than the normal case, and the like, the running load is increased, and the running driving force tends to be insufficient. In this case, if the engine 1 is started with an increase in the required driving force and the step 112 is tried to be passed through in the engine mode or the hybrid mode, there is a possibility that a problem such as that shown in the following reference example may occur.

Fig. 5 is a timing chart showing an example of an operation performed by the control device according to the reference example of the present embodiment, and particularly, as shown in fig. 4, is a timing chart showing an example of an operation when the vehicle 100 runs over the step portion 112 by backward travel. In the figure, a characteristic f10 (two-dot chain line) indicates the required driving force (target driving force) of the vehicle, a characteristic f11 (one-dot chain line) indicates the actual driving force of the engine 1 (engine actual driving force), a characteristic f12 (broken line) indicates the actual driving force of the electric motor 2 (motor actual driving force), and a characteristic f13 (solid line) indicates the actual driving force of the entire vehicle (entire actual driving force) obtained by adding the characteristic f11 and the characteristic f 12. Hereinafter, the maximum actual driving force of the engine 1 is set to be larger than the maximum actual driving force of the motor 2.

As shown in fig. 5, at a time immediately before time t1, vehicle 100 generates the required driving force by the motor running, and engine 1 is stopped. At time t1, when the rear wheel 7R hits the stepped portion 112 and the vehicle 100 stops, the required driving force increases, and the actual motor driving force increases accordingly. At time t2, when the motor actual driving force (more specifically, the motor torque corresponding to the motor actual driving force) reaches a predetermined torque upper limit value (predetermined value Tma) at the time of powering the motor 2, the torque of the motor 2 cannot be increased to the value or more. Therefore, the motor cannot obtain the required driving force, and the engine 1 is started. Then, the actual driving force of the engine increases, and the actual driving force of the motor decreases accordingly.

At this time, a timing deviation as shown in the drawing may occur between an increase in the actual driving force of the engine and a decrease in the actual driving force of the motor due to a communication delay or the like. Therefore, at time t3, the total actual driving force may temporarily exceed the required driving force. As a result, the driving force of the vehicle 100 after the rear wheel 7R has passed over the stepped portion 112 becomes excessively large, and the rear wheel 7R may violently collide with the stopper 113, thereby giving an impact to the occupant. Depending on the situation, the vehicle 100 may collide with the obstacle 114. In order to suppress the occurrence of a collision or the like when the vehicle passes over the step portion, the present embodiment constitutes a control device as follows.

Fig. 6 is a block diagram showing a main configuration of the control device 50 of the present embodiment, particularly a configuration related to parking travel. The control device 50 is a device for moving the vehicle 100 to the parking lot 111 by automatic driving, and constitutes a part of the vehicle control system 101 of fig. 2. As shown in fig. 6, the control device 50 includes: the vehicle control system includes a controller 40, and a vehicle speed sensor 32a, a battery sensor 32b, a torque sensor 32c, an electric power control unit 60, an engine actuator 61, a clutch actuator 62, and a brake actuator 63, which are connected to the controller 40.

The vehicle speed sensor 32a detects the vehicle speed of the vehicle 100 and outputs a detection signal to the controller 40. The battery sensor 32b detects the remaining capacity of the battery 5 and outputs a detection signal to the controller 40. The torque sensor 32c detects the torque of the motor 2 and outputs a detection signal to the controller 40. Since the torque generated by the motor 2 is proportional to the current supplied to the motor 2, the torque sensor 32c can also detect the torque from the current supplied to the motor 2. The vehicle speed sensor 32a, the battery sensor 32b, and the torque sensor 32c constitute a part of the internal sensor group 32 of fig. 2.

The power control unit 60 controls driving of the motor 2 based on a signal from the controller 40, and controls charging and discharging of the battery 5. The engine actuator 61, the clutch actuator 62, and the brake actuator 63 control the engine 1, the clutch 4, and the brake device 6, respectively, based on signals from the controller 40. The motor 2, the engine actuator 61, the clutch actuator 62, and the brake actuator 63 constitute a part of the actuator AC of fig. 2.

The controller 40 has a functional configuration of a required driving force calculation unit 451, a mode switching determination unit 461, a motor control unit 462, an engine control unit 463, a clutch control unit 464, and a brake control unit 465. The required driving force calculation unit 451 constitutes, for example, a part of the action plan generation unit 45, and the mode switching determination unit 461, the motor control unit 462, the engine control unit 463, the clutch control unit 464, and the brake control unit 465 constitute, for example, a part of the travel control unit 46 in fig. 2.

The required driving force calculation unit 451 calculates the required driving force when the vehicle 100 is running in the parked state. For example, the required driving force calculation unit 451 compares the actual vehicle speed detected by the vehicle speed sensor 32a with the target vehicle speed, and gradually increases the required driving force when the actual vehicle speed is smaller than the target vehicle speed.

The mode switching determination section 461 determines whether or not the driving mode during parking travel needs to be switched. In the present embodiment, for example, the parking travel is performed in either the EV mode or the engine mode. Therefore, the mode switching determination part 461 determines whether or not the driving mode needs to be switched from the EV mode to the engine mode and from the engine mode to the EV mode. Specifically, it is determined whether the torque Tm of the electric motor 2 detected by the torque sensor 32c during the motor running is a predetermined value Tma (predetermined torque upper limit value of the electric motor 2) or not, and whether the vehicle speed V detected by the vehicle speed sensor 32a is a predetermined value Va (for example, 0) or less. That is, it is determined whether or not the engine mode switching condition is satisfied. And when Tm is greater than or equal to Tma and V is less than or equal to Va, the switching from the EV mode to the engine mode is determined to be required. That is, it is determined that the engine mode switching condition is satisfied.

The mode switching determination unit 461 also determines whether or not the battery remaining capacity SOC detected by the battery sensor 32b during motor running is equal to or less than a predetermined value SOCa. The predetermined value SOCa is a threshold value for determining whether or not the battery 5 needs to be charged, and when SOC is less than or equal to SOCa, the mode switching determination unit 461 determines that switching from the EV mode to the engine mode is necessary even if Tm < Tma or V > Va. That is, it is determined that the engine mode switching condition is satisfied. The mode switching determination unit 461 determines that switching from the engine mode to the EV mode is not necessary until the parking travel is completed after the driving mode is switched to the engine mode due to the establishment of the engine mode switching condition. Further, when it is determined that the engine mode switching condition is not satisfied after the switching to the engine mode, it may be determined that the switching from the engine mode to the EV mode is necessary.

The motor control unit 462 controls the driving of the motor 2 based on the determination result of the mode switching determination unit 461. That is, when the mode switching determination unit 461 determines that switching from the EV mode to the engine mode is not necessary, the motor control unit 462 outputs a control signal to the electric power control unit 60 to drive the electric motor 2 based on the required driving force calculated by the required driving force calculation unit 451, and controls driving of the electric motor 2. At this time, the required driving force corresponds to the creep force, which is the driving force of the vehicle 100 when the accelerator pedal is released, and the parking travel is performed by the creep travel. On the other hand, when the mode switching determination unit 461 determines that switching to the engine mode is necessary, the motor control unit 462 decreases the actual driving force of the motor to 0 as the actual driving force of the engine increases.

The engine control unit 463 controls driving of the engine 1 based on the determination result of the mode switching determination unit 461. That is, when the mode switching determination unit 461 determines that switching from the EV mode to the engine mode is necessary, the engine control unit 463 outputs a control signal to an engine actuator (engine starting actuator) to start the engine 1 after the brake device 6 is operated and the clutch 4 is disengaged (disengaged). When the clutch 4 is engaged (connected) and the brake device 6 is released after the engine is started, the engine control unit 463 gradually increases the actual engine driving force based on the driving force demand calculated by the driving force demand calculation unit 451.

The clutch control unit 464 controls the operation of the clutch 4 based on the determination result of the mode switching determination unit 461. That is, when the mode switching determination unit 461 determines that switching from the EV mode to the engine mode is necessary, the clutch control unit 464 outputs a control signal to the clutch actuator 62 to release the clutch 4 and cut off the power transmission from the engine 1 to the drive wheels 7. After that, when the engine 1 is started, the clutch control section 464 engages the clutch 4 to transmit power from the engine 1 to the drive wheels 7.

The brake control unit 465 controls the operation of the brake device 6 based on the determination result of the mode switching determination unit 461. That is, when the mode switching determination unit 461 determines that switching from the EV mode to the engine mode is necessary, the brake control unit 465 outputs a control signal to the brake actuator 63 to activate the brake device 6 and forcibly stop the vehicle 100. When engine 1 is started, brake control unit 465 releases brake device 6 to enable vehicle 100 to run the engine.

Fig. 7 is a flowchart showing an example of processing performed by the CPU of the controller 40 in fig. 6 according to a program stored in advance in the storage unit 42. The processing shown in this flowchart is started when the vehicle 100 is instructed to move to the parking lot 111, for example, as shown in fig. 3, and is repeated at a predetermined cycle. At the start of control, the vehicle 100 is operated in the EV mode.

First, at S1 (S: processing step), the required driving force is calculated from a deviation or the like between the target vehicle speed during parking travel and the actual vehicle speed detected by the vehicle speed sensor 32 a. Next, at S2, it is determined whether or not the remaining capacity SOC of the battery 5 detected by the battery sensor 32b is equal to or less than a predetermined value SOCa, that is, whether or not the battery 5 needs to be charged. If S2 is affirmative (S2: yes), the engine mode switching condition is determined to be satisfied, and the routine proceeds to S3, where a control signal is output to the electric power control unit 60 so that the actual motor driving force (motor torque) becomes 0. Next, at S4, a control signal is output to the brake actuator 63 to actuate the brake device 6, and a control signal is output to the clutch actuator 62 to release the clutch 4.

Next, at S5, a control signal is output to the engine actuator 61 (for example, a starter motor) to start the engine 1. Next, at S6, a control signal is output to the clutch actuator 62 to engage the clutch 4, and a control signal is output to the brake actuator 63 to release the brake device 6. Next, at S7, a control signal is output to the engine actuator 61 based on the required driving force calculated at S1, and the vehicle 100 is caused to run.

On the other hand, if S2 is negative (S2: No), the routine proceeds to S8, where it is determined whether or not the torque Tm of the motor 2 detected by the torque sensor 32c is equal to or greater than a predetermined value Tma. S9 is entered when S8 is affirmative (S8: YES), and S10 is entered when S9 is passed on (S8: NO). At S9, it is determined whether or not the vehicle speed V detected by the vehicle speed sensor 32a is equal to or less than a predetermined value Va. If S9 is affirmative (S9: yes), the engine mode switching condition is determined to be established, and the routine proceeds to S3, whereas if it is negative (S9: no), the routine proceeds to S10. At S10, a control signal is output to the electric power control unit 60 based on the required driving force calculated at S1, and the vehicle is caused to perform EV running (motor running).

The main operation of the control device for a hybrid vehicle according to the present embodiment will be described. Fig. 8 is a timing chart showing an example of an operation when switching from the motor running to the engine running in the parking running. As shown in fig. 8, in the initial state, the vehicle 100 is creeping in the EV mode, the engine actual driving force Fe is 0, and the total actual driving force Ft of the vehicle 100 is equal to the motor actual driving force Fm (S10). At this time, the braking force Fb is 0, and the clutch 4 is in the disengaged state.

At time t1, when the rear wheel 7R hits the stepped portion 112 and cannot get over the stepped portion 112, the vehicle speed V becomes 0. At this time, the required driving force increases, and the motor actual driving force Fm and the entire actual driving force Ft gradually increase. The predetermined value Fma in fig. 8 corresponds to the predetermined value Tma (fig. 5) of the motor torque Tm, and when the motor actual driving force Fm reaches the predetermined value Fma, it is determined that the engine mode switching condition is satisfied at time t 2. Therefore, the motor actual driving force Fm and the entire actual driving force Ft become 0, the brake device 6 is operated, and the braking force Fb is increased to the predetermined value Fb1(S3, S4). Thereby, the vehicle 100 is forced to stop completely.

Thereafter, the engine 1 is started, the clutch 4 is engaged, and the brake device 6 is released (S5, S6). Therefore, at time t3, the engine actual driving force Fe increases, and the total actual driving force Ft becomes a value Ft2 larger than the maximum actual driving force Ft1 during motor running. Thus, vehicle 100 can go over step 112 by engine running, and vehicle speed V becomes greater than 0. At this time, the timing deviation between the motor actual driving force Fm and the engine actual driving force Fe does not occur, and therefore the entire actual driving force Ft does not overshoot the required driving force. Therefore, the occurrence of collision when crossing the step portion can be suppressed. During the subsequent engine running, the vehicle 100 runs by the creep force of the engine 1 while the brake device 6 is adjusted so that the vehicle speed becomes the target vehicle speed.

The present embodiment can provide the following effects.

(1) The control device 50 of the hybrid vehicle has an engine 1 and a motor 2 as a travel drive source, and has a brake device 6 (fig. 1) that applies a braking force to stop the vehicle 100. The control device 50 includes: an engine control unit 463, a motor control unit 462, and a brake control unit 465 that control the engine 1 and the motor 2 in accordance with the required driving force and control the brake device 6; and a mode switching determination unit 461 that determines whether or not the required driving force can be generated while keeping the motor running in a parking operation for parking the vehicle 100 in a predetermined space, in the motor running by driving only the motor 2, in the engine running by driving only the engine 1, and in the hybrid running by driving both the motor 2 and the engine 1 (fig. 6). When the mode switching determination unit 461 determines that the required driving force cannot be generated while the motor is kept running, the engine control unit 463, the motor control unit 462, and the brake control unit 465 decrease the driving force of the motor 2, more specifically, set the actual driving force of the motor to 0, activate the brake device 6 and start the engine 1, and release the activation of the brake device 6 after the engine 1 is started (fig. 7).

In this way, when the required driving force cannot be generated while the motor travel is maintained during the parking operation by the motor travel, the actual driving force of the motor is set to 0 and the engine 1 is started while the brake device 6 is actuated, so that the switching from the EV mode to the engine mode can be performed satisfactorily. That is, when switching from the EV mode to the engine mode, overshoot of the actual driving force due to timing deviation between an increase in the actual driving force of the engine and a decrease in the actual driving force of the motor can be prevented, and the parking travel requiring positional accuracy can be performed satisfactorily.

(2) The control device 50 of the hybrid vehicle further includes a vehicle speed sensor 32a, and the vehicle speed sensor 32a detects a vehicle speed V (fig. 6). The mode switching determination unit 461 determines that the required driving force cannot be generated while the motor running is maintained, when the vehicle speed V detected by the vehicle speed sensor 32a is equal to or less than the predetermined value Va (for example, 0) even though the driving force (torque) of the motor 2 is increased to the predetermined value Tma, which is the maximum value, during the parking operation by the motor running (S8, S9). Accordingly, when vehicle 100 cannot get over the stepped portion, the EV mode is switched to the engine mode in the stopped state, so that the actual driving force does not become excessively large, and vehicle 100 can easily get over stepped portion 112.

(3) The vehicle 100 further includes a battery 5, and the battery 5 supplies electric power to the electric motor 2 (fig. 1). The control device 50 further includes a battery sensor 32b, and the battery sensor 32b detects a remaining capacity SOC of the battery 5 (fig. 6). The mode switching determination unit 461 determines that the required driving force cannot be generated while the motor is kept running, when the remaining capacity SOC of the battery 5 detected by the battery sensor 32b is equal to or less than the predetermined value SOCa during the parking operation by the motor running (S2). Thus, when the amount of charge of the battery 5 is insufficient during parking travel, the actual driving force does not become excessively large, and the driving mode can be switched from the EV mode to the engine mode in a satisfactory manner.

(4) The vehicle 100 also has a clutch 4, and the clutch 4 transmits or does not transmit the driving force of the engine 1 to the drive wheels 7 (fig. 1). When the mode switching determination unit 461 determines that the required driving force cannot be generated while the motor is kept running, the clutch control unit 464 (fig. 6) switches the clutch 4 so that the driving force of the engine 1 is not transmitted to the drive wheels 7 before the engine 1 is started (S4). This can reliably prevent the actual driving force of the engine from being transmitted to the drive wheels 7 until the start of the engine 1 is completed.

(5) The vehicle 100 is an autonomous vehicle having an autonomous driving function (fig. 2). Accordingly, since the driver does not need to operate the accelerator pedal during the parking travel, it is possible to suppress a sense of discomfort given to the driver due to the vehicle actual driving force temporarily becoming 0 and the vehicle 100 forcibly stopping when switching the mode from the EV mode to the engine mode is performed.

The above embodiments can be modified into various forms. The following describes modifications. In the above embodiment, when the engine mode switching condition is satisfied, the travel control unit 46 switches the driving mode from the EV mode to the engine mode, but may also switch to the hybrid mode. In the above embodiment, the maximum driving force of the engine 1 is set to be larger than the maximum driving force of the electric motor 2, but particularly when the driving mode is switched to the hybrid mode, the maximum driving force of the engine 1 may be smaller than the maximum driving force of the electric motor 2.

In the above embodiment, when switching from the EV mode to the engine mode during parking travel, the travel control unit 46 controls the engine 1, the electric motor 2, the clutch 4, and the brake device 6 in accordance with the required driving force, but the configuration of the travel control unit 46 may be any configuration as long as at least the engine 1, the electric motor 2, and the brake device 6 (brake device) are controlled. That is, the travel control unit 46 may have any configuration as long as the driving force of the electric motor 2 is reduced, the brake device 6 is operated, the engine 1 is started, and the operation of the brake device 6 is released after the engine 1 is started. In the above embodiment, the clutch 4 is switched when the mode switching is performed during the parking travel, but the clutch 4 may not be controlled. In the above embodiment, the clutch 4 is provided between the engine 1 and the transmission 3, but the configuration of the power transmission mechanism is not limited to this, and for example, the power transmission mechanism may be provided in the transmission 3.

In the above embodiment, the mode switching determination unit 461 determines that the engine mode switching condition is satisfied when the torque Tm of the electric motor 2 is equal to or greater than the predetermined value Tma and the vehicle speed V is equal to or less than the predetermined value Va, and when the remaining capacity SOC of the battery 5 is equal to or less than the predetermined value SOCa. However, the determination unit may be configured in any form as long as it determines whether the required driving force can be generated while keeping the motor running during the parking operation. For example, the height of the step 112 may be detected by a camera or the like, and the determination unit may determine that the required driving force cannot be generated while keeping the motor running when the height of the step 112 is equal to or greater than a predetermined value. The determination unit determines whether the vehicle 100 (wheels) can travel by the motor to cross the step 112 of the road surface of the parking lot 111 based on the signal from the vehicle speed sensor 32a or the like, and if it is determined that the vehicle cannot cross the step 112, it may be determined that the required driving force cannot be generated while keeping the motor traveling. In the above embodiment, the vehicle speed is detected by the vehicle speed sensor 32a, but the vehicle speed detection unit may be configured in any form. It is also possible to determine whether the required driving force can be generated while the motor is being held, based on the variable of the absolute position of the vehicle 100 detected by the GPS device 34. In the above embodiment, the remaining capacity SOC of the battery 5 as a secondary battery is detected by the battery sensor 32b, but the configuration of the remaining capacity detecting unit may be any configuration.

In the above-described embodiment, the control device 50 is applied to the autonomous vehicle 100, but the control device of the hybrid vehicle of the present invention can be similarly applied to a vehicle having only a part of the autonomous function, such as a vehicle having a parking assist device. The present invention can also be applied to a vehicle that performs parking travel by manual driving.

One or more of the above embodiments and modifications may be arbitrarily combined, or modifications may be combined with each other.

The present invention can increase the driving force favorably when the required driving force cannot be generated during parking driving while traveling by the motor.

While the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the disclosure of the following claims.

Claims (8)

1. A control device for a hybrid vehicle, which has an engine (1) and an electric motor (2) as travel drive sources and a brake device (6) that applies a braking force to stop a vehicle (100), is characterized by comprising:

a travel control unit (463, 462, 465) that controls the engine (1) and the motor (2) in accordance with a required driving force and controls the brake device (6); and

a determination unit (461) that determines whether or not a required driving force can be generated while maintaining the motor travel in a parking operation in which the hybrid vehicle (100) is parked in a predetermined space (111) during the motor travel in a motor travel using only the drive of the motor (2), an engine travel using only the drive of the engine (1), and a hybrid travel using both the drives of the motor (2) and the engine (1),

when the determination unit (461) determines that the required driving force cannot be generated while the motor is kept running, the running control unit (463, 462, 465) reduces the driving force of the motor (2), activates the brake device (6) and starts the engine (1), and releases the operation of the brake device (6) after the engine (1) is started.

2. The control device of a hybrid vehicle according to claim 1,

further comprises a vehicle speed detection unit (32a) for detecting the vehicle speed,

the determination unit (461) determines that the required driving force cannot be generated while the motor running is maintained, when the vehicle speed detected by the vehicle speed detection unit (32a) is equal to or less than a predetermined value (Va), even though the driving force of the motor (2) is increased to a maximum value (Tma) during the parking operation in the motor running.

3. The control device of a hybrid vehicle according to claim 1,

the hybrid vehicle (100) further includes a secondary battery (5), the secondary battery (5) supplying electric power to the electric motor (2),

the control device for a hybrid vehicle further has a remaining capacity detection unit (32b), the remaining capacity detection unit (32b) detecting the remaining capacity of the secondary battery (5),

the determination unit (461) determines that the required driving force cannot be generated while the motor is kept running, when the remaining capacity of the secondary battery (5) detected by the remaining capacity detection unit (32b) is equal to or less than a predetermined value (SOCa) during parking operation while the motor is running.

4. The control device of a hybrid vehicle according to claim 1,

the determination unit (461) determines whether or not the hybrid vehicle (100) can cross a step (112) provided on a road surface of the predetermined space (111), and determines that the required driving force cannot be generated while keeping the motor running when it is determined that the hybrid vehicle cannot cross the step (112).

5. The control device of a hybrid vehicle according to any one of claims 1 to 4,

the hybrid vehicle (100) further has a power transmission mechanism (4), the power transmission mechanism (4) transmitting or not transmitting the driving force of the engine (1) to a drive wheel (7),

when the determination unit (461) determines that the required driving force cannot be generated while the motor is kept running, the running control unit (464) switches the power transmission mechanism (4) so that the driving force of the engine (1) is not transmitted to the driving wheels (7) before the engine (1) is started.

6. The control device of a hybrid vehicle according to any one of claims 1 to 5,

the hybrid vehicle (100) is an autonomous vehicle having an autonomous driving function.

7. The control device of a hybrid vehicle according to any one of claims 1 to 6,

when the determination unit (461) determines that the required driving force cannot be generated while the motor is kept running, the running control unit (462) sets the driving force of the motor (2) to 0 so that the required driving force is generated during the engine running.

8. A control method of a hybrid vehicle having an engine (1) and an electric motor (2) as travel drive sources and having a brake device (6) that applies a braking force to stop a vehicle (100), characterized by comprising the steps of:

controlling the engine (1) and the motor (2) according to a driving force demand, and controlling the brake device (6); and

determining whether or not a required driving force can be generated while maintaining the motor running, in a parking drive in which the hybrid vehicle (100) is parked in a predetermined space (111), during the motor running in a motor running in which only the motor (2) is driven, an engine running in which only the engine (1) is driven, and a hybrid running in which both the motor (2) and the engine (1) are driven,

the step of controlling includes, when it is determined in the step of determining that the required driving force cannot be generated while the motor is kept running, decreasing the driving force of the motor (2), operating the brake device (6) and starting the engine (1), and releasing the operation of the brake device (6) after the engine (1) is started.

Images